“Biofilm” generally refers to communities of microorganism encased by extracellular polymeric substances, and is prevalent in natural, industrial, and clinical settings. Biofilms enhance survival, enabling organisms to adapt to changing conditions collectively instead of as single cells, and bring serious harm to human. For example, in medicine field, researches have indicated that about 65% human bacterial infections are related to biofilms, and antibiotics resistance of the microorganisms in the biofilms is hundreds or even thousands of times higher than that in a planktonic state, which greatly increases difficulties for clinical treatment.
Biofilm bacteria show extreme tolerance to almost all antibiotic classes. One of the most important features of biofilms is self-secreted extracellular polymeric substances consisting of mainly polysaccharides, proteins, and lipoproteins, which function as a matrix, holding biofilm cells together and protecting cells from antibiotics. By forming a matrix-encased multicellular aggregate, cells can also escape engulfment by phagocytic cells within a mammalian host. Extracellular polymeric substances not only promote bacteria to attach all kinds of surfaces (for example, a biomedical material or a mucosal surface of a biological organism), but also trap antibiotics or influence antibiotics to penetrate into the bacterial communities. Therefore, most drugs may only kill microorganisms on outer layer of the biofilm, yet microorganisms inside the biofilm may be the main reason for the generation of antibiotic-resistant mutation. Thus the biofilm may become a potential source of infections, which may cause refractory infections relating to clinical biofilms.
Pseudomonas aeruginosa (PA) is an environmental bacterium, and it is also an important human pathogen that may cause life-threatening persistent infections in humans, especially for burned patients and immune-compromised patients, and is the common pathogen in hospital-acquired infections. The persistence of Pseudomonas aeruginosa during these infections has been linked to its ability to form biofilms. Clinically, Pseudomonas aeruginosa may cause infections of blood, ears, eyes, skin and soft tissue, bone and joints, endocardium, respiratory system, etc. It is also the primary pathogen for causing pneumonia. Due to the intrinsic resistance of Pseudomonas aeruginosa to antibiotics and its biofilm formation ability, Pseudomonas aeruginosa infections are difficult to eradicate.
Therefore, there is an urgent need in the art for developing a preparation and a method for effectively inhibiting or disrupting a biofilm of a microorganism such as Pseudomonas aeruginosa. 